For the last decade or so, health experts have thought that they had the whole childhood obesity thing figured out. According to all of the research, obesity in kids is linked to inactivity and poor eating habits. So by encouraing kids to play sports or make healthier dietary choices - such as drinking low-fat milk - at lunch, one could reduce a child's overall obesity risk, right? Well, that depends. An ew study has found that certain obesity risk factors may be gender specific.

For example, the study found that involvement in sports helped boys lower their risk for childhood obesity, but not girls. And girls who drank milk as part of a healthy diet were less likely to be obese, but the same was not true for boys.

The study used data collected between 2004 and 2011 from 1,714 sixth-grade students at 20 middle schools in the Michigan area. Overall, about 18 percent of boys and 16 percent of girls evaluated in the study were considered obese using body mass index measurements.

Of the boys who were not obese, 56 percent played sports for at least 20 minutes a day, 5 days per week. The number was only 43 percent for the boys who fell into the 'obese' category. But for girls, there was no difference at all in the percentage of obese and non-obese girls who reported participating in regular physical activity.

On the other hand, researchers found that girls who drank two or more servings of milk per day were 20 percent less likely to be obese. But the same risk reduction was not seen for boys.

Other risk factors - such as TV watching and school lunch consumption - were similar for both boys and girls across the study. Boy or girl, kids who watched two or more hours of TV each day were 19 percent more likely to be obese. And kids who ate school lunches were a whopping 27-29 percent more likely to be obese - regardless of gender.

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